<!DOCTYPE html> 
<html> 
<head> 
<meta charset=" utf-8"> 
<meta name="author" content="http://www.softwhy.com/" />
<head>
<title>蚂蚁部落</title> 
<style type="text/css">
*{
	margin: 0;
	padding: 0;
}
	div:nth-child(1){
		width: 100px;
		height: 100px;
		border: 1px solid red;
		position: relative;
		left: 100px;
	}
	div:nth-child(2){
		width: 100px;
		height: 100px;
		border: 1px solid #333;
		position: absolute;
		top: 50px;
	}
</style>
<script type="text/javascript">
	var a=1;
	function t() {
		alert(a);
		var a="";
	}
	t();
</script>
</head> 
<body> 
	<div>461843</div>
	<div>49864</div>
</body> 
</html>